Car differential. Problems, symptoms, and replacement costs

One of the important parts of the car is the differential. Many drivers do not know of its existence, and those who know, do not give it much importance. The differential requires special and regular care.

What does a car differential do?

The main task of the differential is to distribute, change, and then transmit rotation. In short, the differential transmits the engine’s torque to the wheels. If necessary, the differential provides torsion of two elements with different angular speeds.

The device turns one of the car wheels, after which the other wheel begins to rotate in the opposite direction. However, the driveshaft must remain immobilized. In this situation, the satellites rotate on their axis, playing the role of gears.

After starting the engine, pressing the clutch pedal, and putting the gearshift in any gear, the driveshaft begins to rotate and transmit the moment of rotation.

As a result, when the car is in a turn, one wheel slows down, and the second begins to rotate faster. This will cause sliding not to occur.

At the same time, each of the wheels rotates at the speed that is necessary for safe movement. If the car is moving in a straight line, then no special actions occur.

In this case, the differential transmits the moment of rotation to a pair of wheels in an identical ratio.

If the car is on a slippery surface, then a side skid may occur which is one of the differential disadvantages, because the clutch force acting on the towing wheel is low, which is why the rotation is wasted.

For modern cars, however, differentials have almost no disadvantages. The design of differentials is defined by the presence of rigid adjustment, which can be performed manually or automatically.

In addition, on modern cars, a system of directional stability and stabilization is provided, thanks to which the torque is optimized.

Where is the differential located?

For AWD (all-wheel-drive) cars in the transfer case;
For 4×4 cars FWD – Four Wheel Drive in axle housing (front or back);
For cars with front-wheel-drive in the transmission;
For vehicles with rear-wheel-drive in the rear axle housing.

Types of differential

The types of car differential are based on a planetary gearbox, which uses a special transmission of the gear type. In this case, the device can be of several types:

  • conical
  • worm
  • cylindrical.

The most common type of car differential is the worm differential, which is mounted between the wheels or between the axles. There are two other types of differential that are worth mentioning:

  • Asymmetrical. This type of device is especially suitable for mounting between two drive axes. You can use it to transmit the moment of rotation in different proportions.
  • Symmetrical – mounted on the main gears. Its feature is the transfer of equal torque to both wheels

Symptoms of a bad car differential

Signs of differential failures are possible:

  • Excessive noise level;
  • Leaks of the lubricating fluid;
  • Strong knocks and bumps in the transmission.

In most cases, if you hear noises while driving is better to check the crankcase temperature level. It should be 55-60 degrees Celsius (131-140 degrees Fahrenheit). If the temperature is above these values, you should check if the crankcase has sufficient oil and its quality.

If after you checked and repaired the crankcase problem the noise is still heard, you should check the differential. The causes may be worn-out bearings and gear teeth damage. You can fix these problems if you adjust or replace the differential.

How to check a bad car differential?

There is an easy way to check a failing differential. All you need is a jack and someone who can help you.

Put the gearshift in the neutral position, then lift the car with the jack. Move the wheel in one direction and the other.

At the same time, ask the assistant to move the other wheel in the opposite direction. By the type of rotation, you can know if the differential has problems.

So, if you move the wheels in different directions without problems, without knocks and noises, then the differential has no issues.

If the wheels move only in one direction, and in the other direction you can hear knocks and noises, then there are obvious problems with the differential.

If you can’t identify the problem yourself, then you should contact the professionals in a car service. Skilled mechanics not only will identify the problem but also will fix it in a short time.

What are the causes of a bad differential?

The most common cause is the wear of the satellite axis. Drivers who love speed and extreme driving are more prone to see this happen early. In this case, the damage process takes place in several key stages.

  • Bad lubrication quality of nodes. It is no secret that during extreme braking, classic lubrication schemes lose efficiency, which is why satellites do not have enough oil;
  • Overheating of the working units. Due to overheating, the hardness of the outer layer of the satellite axis decreases, which causes rapid wear;
  • Failures. Over time, failures occur that lead to a change in the position of the differential elements. As a result, the key components of the device will be damaged. In situations where the wear level reaches a critical point, the axle is broken and the gears fall out of the differential. For this reason, the integrity of the transmission is compromised.

In the usual operating conditions, the differential requires special attention from the owner. It is known that not only the engine oil must be monitored, but also the level of the transmission fluid.

If you do not notice a decrease in the oil level in time, then due to a lack of lubrication, the integrity of the oil seals and various seals may be compromised. As a result, the differential and satellites may be damaged.

Can the car differential be repaired?

The short answer is yes. The repair begins by removing the device, after which (if necessary) the unit is disassembled and the condition of its components is evaluated.

As practice shows, there are many components of the differential that are worn and can be replaced, and if you find the right workshop, you can save money.

Can the differential be disabled?

Some drivers ask that question. The action of this car part is aimed to increase the car’s cross-country ability.

With the help of the differential, the wheels receive a uniform moment of rotation from the power unit. Turning off the differential will decrease the car’s cross-country potential. FWD (for-wheel-drive) cars have this feature.

How much does it cost to repair or replace the car differential?

The cost of repairing both the front and rear differential will depend on what repairs are needed. In most cases, you just need to replace the fluid seals of the differential. Depending on your car, these simple repairs can cost between $180 and $400.

If you need to remove the differential and perform a detailed check, costs can vary between $450 and $800.

If you need a complete replacement of the differential expect higher costs that can be between $1000 and approximately $6000. These high differences in prices are due to the choice you make when you buy a used or a new differential.

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